I need to find a good low voltage cutoff circuit for LiPo batteries

[Razor512]

Hi, I have a few LiPo batteries which have their own built in protection circuits, but the low voltage protection of the battery seems to kick in around 2.75V, but I am not comfortable discharging them them that far. I would instead like to have a cutoff at around 3.2V instead.

The problem is that I will be using it to power a device that had previously used 3V non rechargeable lithium batteries (I have regulation taken care of using a boost-buck converter), and it will take batteries down to 2.5V, thus if used with used with the LiPo cell, it will always drain the battery to a point where the protection circuit kicks in.

I am using some cheaper shenzhen market 4000mAh LiPo cells which is another reason why I am not comfortable with draining them to 2.75V.

I am mainly looking for a power efficient way to implement a low voltage cutoff, with the intention of powering a device that will only consume around 50mA of power.

[JacquesBBB]

You can just get one of these  1$ modules for charging and discharging the lipo cells. I use them all the time on my
batteries.  They cut the power around  3.2 V (Not sure ....). They also can  monitor the charging with USB.

I can also say that G&C is a very reliable and fast (?)  ebay  seller.

http://www.ebay.fr/itm/1pcs-5V-MICRO-USB-1A-Lithium-Battery-Charging-Protection-in-one-Board-Module-/300919267742?pt=LH_DefaultDomain_0&hash=item46102fa19e

[jct]

Look at TPS3809 (from Texas Instruments), alternative MAX809 from Maxim; available in various voltages from 2.5 up to 3.5. Attached is just a "Battery OK" and "Low Voltage" indicator, but will give you an idea how to impliment in your application.

[Razor512]

For the $1 units, I was really interested in them, but all of them seem to have a low voltage cutoff of 2.5V which will make the battery hit its own 2.75V cutoff.

I might have to build one if there are no modules. I just hope I don't end up with a situation where the protection circuit uses a ton of power.

A 2.75V cutoff just makes me uncomfortable, it just seems way too low for such a battery.

[sparx]

For the $1 units, I was really interested in them, but all of them seem to have a low voltage cutoff of 2.5V which will make the battery hit its own 2.75V cutoff.

I might have to build one if there are no modules. I just hope I don't end up with a situation where the protection circuit uses a ton of power.

A 2.75V cutoff just makes me uncomfortable, it just seems way too low for such a battery.

Have a look at the datasheet (if available for the chip used) - maybe changing a resistor will change the cutoff.